1. Field of the Invention
The present invention relates to an input-output circuit that is disposed between a connector including a power feeding terminal and a data communication terminal and an internal circuit.
2. Description of the Related Art
Recently, smartphones have been rapidly come into wide use. In many smartphones, in order to improve the designability or decrease the circuit scale, a connector is attempted to be used in common. For example, models only having a micro-USB connector are also available in the market. In such models, in addition to power feeding and data communication, transmission/reception of an audio signal is performed through one micro-USB connector. Such commonization of a connector has been attempted also in other mobile devices such as a cellular phone, a small-sized PC, a digital camera, a portable music player, an IC recorder, and a game machine.
While there is such a trend of the communization of a connector, the number of kinds of devices, chargers, and accessories connected to each mobile device has been increased every year, and it becomes difficult for the mobile device side to determine a member that is connected thereto.
When a mobile device is charged, there are many cases where it is charged by using a charger that is not dedicated thereto. In the market, a variety of chargers other than dedicated chargers are available. Since charging currents of the chargers are not uniformized, it is necessary to allow a charging circuit that is disposed inside the mobile device to recognize the kind of charger.
However, an erroneous detection of the charger may occur due to the shape of a plug socket to be inserted into the connector, deviation of a user's insertion timing, running-out of a battery, or the like. For example, the kind of charger may be erroneously detected.